Gold Filled / Gold Double
Also: Double, Gold-Filled, Rolled Gold, Doublé
Gold filled (gold double) is a base metal core (usually brass or copper) mechanically bonded to a thick gold layer by hot-rolling — in contrast to electrolytic gold plating.
Gold filled (also Doublé, or in English Rolled Gold) refers to a composite material in which a relatively thick layer of gold is permanently bonded to a base metal substrate — typically brass, copper, or nickel silver — by mechanical hot-rolling or pressing. The result is visually almost indistinguishable from solid gold, yet contains only a fraction of gold's value.
Manufacturing and Structure
In the gold-filled process, a gold sheet (usually 333 to 750 alloy) is rolled together with the base metal at high temperature until both layers form an inseparable metallic bond. The gold layer accounts for at least 1/20 of the total weight (the American Gold Filled standard) and at 20–100 micrometres is significantly thicker than an electrolytic gold plating (0.1–5 µm). This layer thickness gives gold filled material considerably better wear resistance.
Distinctions: Gold Filled, Electroplating, Doublé
| Feature | Gold Filled | Electroplating | Solid Gold |
|---|---|---|---|
| Bond type | Mechanical (rolling) | Electrolytic | Monolithic |
| Layer thickness | 20–100 µm | 0.1–5 µm | Full material |
| Gold share by weight | approx. 5 % | < 0.1 % | 100 % |
| Durability | High (years to decades) | Low to medium | Permanent |
| Overall fineness | Below 333 ‰ | Below 333 ‰ | Varies by alloy |
Important: Since the fineness of the complete piece is generally below 333 parts per thousand, gold filled material is not considered a precious metal under German precious-metal law and may not be hallmarked with a genuine gold stamp.
Labelling and Legal Position
In Germany and the EU, gold filled material must be clearly labelled as such — typical markings are GF (Gold Filled), RG (Rolled Gold), Doublé, or a specification such as 20/1000 GF 14K. Misleading use of the term "gold" or the application of a genuine gold hallmark is prohibited. In the United States, the FTC Jewelry Guides govern the minimum requirements for gold-filled jewellery.
The actual material value can be estimated using the Melt Value Calculator — however, for gold-filled items only the weight of the gold layer is relevant, not the total weight. Whether a piece is genuinely gold filled or solid gold can be determined by authenticity testing or a professional streak/acid test at a jeweller.
Formulae for the Gold Content
Gold weight = Total weight × (layer share / 1000) × (fineness in karat / 24)
Example: 10 g bracelet, 1/20 GF, 14K → 10 × 0.05 × 0.583 ≈ 0.29 g fine gold
In Brief
Gold filled offers the visual appearance of gold at a fraction of the price, but possesses no significant material value as a precious metal. For buying and refining purposes, the actual fine gold content is decisive — this can be determined with the Buying Price Calculator once the layer parameters are known.